/*
 * Copyright (c) 2007, 2015, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
/*
 * Copyright 2000-2002,2004 The Apache Software Foundation.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.sun.org.apache.xerces.internal.impl.io;

import java.io.InputStream;
import java.io.IOException;
import java.io.Reader;
import java.util.Locale;
import com.sun.org.apache.xerces.internal.util.MessageFormatter;
import com.sun.org.apache.xerces.internal.impl.msg.XMLMessageFormatter;

import com.sun.xml.internal.stream.util.BufferAllocator;
import com.sun.xml.internal.stream.util.ThreadLocalBufferAllocator;

/**
 * A simple ASCII byte reader. This is an optimized reader for reading
 * byte streams that only contain 7-bit ASCII characters.
 *
 * @author Andy Clark, IBM
 * @xerces.internal
 */
public class ASCIIReader
    extends Reader {

  //
  // Constants
  //

  /**
   * Default byte buffer size (2048).
   */
  public static final int DEFAULT_BUFFER_SIZE = 2048;

  //
  // Data
  //

  /**
   * Input stream.
   */
  protected InputStream fInputStream;

  /**
   * Byte buffer.
   */
  protected byte[] fBuffer;

  // message formatter; used to produce localized
  // exception messages
  private MessageFormatter fFormatter = null;

  //Locale to use for messages
  private Locale fLocale = null;

  //
  // Constructors
  //

  /**
   * Constructs an ASCII reader from the specified input stream
   * using the default buffer size.
   *
   * @param inputStream The input stream.
   * @param messageFormatter the MessageFormatter to use to message reporting.
   * @param locale the Locale for which messages are to be reported
   */
  public ASCIIReader(InputStream inputStream, MessageFormatter messageFormatter,
      Locale locale) {
    this(inputStream, DEFAULT_BUFFER_SIZE, messageFormatter, locale);
  } // <init>(InputStream, MessageFormatter, Locale)

  /**
   * Constructs an ASCII reader from the specified input stream
   * and buffer size.
   *
   * @param inputStream The input stream.
   * @param size The initial buffer size.
   * @param messageFormatter the MessageFormatter to use to message reporting.
   * @param locale the Locale for which messages are to be reported
   */
  public ASCIIReader(InputStream inputStream, int size,
      MessageFormatter messageFormatter, Locale locale) {
    fInputStream = inputStream;
    BufferAllocator ba = ThreadLocalBufferAllocator.getBufferAllocator();
    fBuffer = ba.getByteBuffer(size);
    if (fBuffer == null) {
      fBuffer = new byte[size];
    }
    fFormatter = messageFormatter;
    fLocale = locale;
  } // <init>(InputStream,int, MessageFormatter, Locale)

  //
  // Reader methods
  //

  /**
   * Read a single character.  This method will block until a character is
   * available, an I/O error occurs, or the end of the stream is reached.
   *
   * <p> Subclasses that intend to support efficient single-character input
   * should override this method.
   *
   * @return The character read, as an integer in the range 0 to 127 (<tt>0x00-0x7f</tt>), or -1 if
   * the end of the stream has been reached
   * @throws IOException If an I/O error occurs
   */
  public int read() throws IOException {
    int b0 = fInputStream.read();
    if (b0 >= 0x80) {
      throw new MalformedByteSequenceException(fFormatter,
          fLocale, XMLMessageFormatter.XML_DOMAIN,
          "InvalidASCII", new Object[]{Integer.toString(b0)});
    }
    return b0;
  } // read():int

  /**
   * Read characters into a portion of an array.  This method will block
   * until some input is available, an I/O error occurs, or the end of the
   * stream is reached.
   *
   * @param ch Destination buffer
   * @param offset Offset at which to start storing characters
   * @param length Maximum number of characters to read
   * @return The number of characters read, or -1 if the end of the stream has been reached
   * @throws IOException If an I/O error occurs
   */
  public int read(char ch[], int offset, int length) throws IOException {
    if (length > fBuffer.length) {
      length = fBuffer.length;
    }
    int count = fInputStream.read(fBuffer, 0, length);
    for (int i = 0; i < count; i++) {
      int b0 = fBuffer[i];
      if (b0 < 0) {
        throw new MalformedByteSequenceException(fFormatter,
            fLocale, XMLMessageFormatter.XML_DOMAIN,
            "InvalidASCII", new Object[]{Integer.toString(b0 & 0x0FF)});
      }
      ch[offset + i] = (char) b0;
    }
    return count;
  } // read(char[],int,int)

  /**
   * Skip characters.  This method will block until some characters are
   * available, an I/O error occurs, or the end of the stream is reached.
   *
   * @param n The number of characters to skip
   * @return The number of characters actually skipped
   * @throws IOException If an I/O error occurs
   */
  public long skip(long n) throws IOException {
    return fInputStream.skip(n);
  } // skip(long):long

  /**
   * Tell whether this stream is ready to be read.
   *
   * @return True if the next read() is guaranteed not to block for input, false otherwise.  Note
   * that returning false does not guarantee that the next read will block.
   * @throws IOException If an I/O error occurs
   */
  public boolean ready() throws IOException {
    return false;
  } // ready()

  /**
   * Tell whether this stream supports the mark() operation.
   */
  public boolean markSupported() {
    return fInputStream.markSupported();
  } // markSupported()

  /**
   * Mark the present position in the stream.  Subsequent calls to reset()
   * will attempt to reposition the stream to this point.  Not all
   * character-input streams support the mark() operation.
   *
   * @param readAheadLimit Limit on the number of characters that may be read while still preserving
   * the mark.  After reading this many characters, attempting to reset the stream may fail.
   * @throws IOException If the stream does not support mark(), or if some other I/O error occurs
   */
  public void mark(int readAheadLimit) throws IOException {
    fInputStream.mark(readAheadLimit);
  } // mark(int)

  /**
   * Reset the stream.  If the stream has been marked, then attempt to
   * reposition it at the mark.  If the stream has not been marked, then
   * attempt to reset it in some way appropriate to the particular stream,
   * for example by repositioning it to its starting point.  Not all
   * character-input streams support the reset() operation, and some support
   * reset() without supporting mark().
   *
   * @throws IOException If the stream has not been marked, or if the mark has been invalidated, or
   * if the stream does not support reset(), or if some other I/O error occurs
   */
  public void reset() throws IOException {
    fInputStream.reset();
  } // reset()

  /**
   * Close the stream.  Once a stream has been closed, further read(),
   * ready(), mark(), or reset() invocations will throw an IOException.
   * Closing a previously-closed stream, however, has no effect.
   *
   * @throws IOException If an I/O error occurs
   */
  public void close() throws IOException {
    BufferAllocator ba = ThreadLocalBufferAllocator.getBufferAllocator();
    ba.returnByteBuffer(fBuffer);
    fBuffer = null;
    fInputStream.close();
  } // close()

} // class ASCIIReader
